The present invention relates to the grinding of tires. The invention proposes a method of grinding new or used tires and proposes a machine for the grinding on the vehicle of a tire which has previously been installed on the vehicle.
Tire grinding operations are well known and are described, for instance, in U.S. Pat. Nos. 3,943,806 and 4,936,054. The purpose of the grinding operation, as known in the state of the art, is to improve or restore a certain perfection of the shape of the tire so as to improve its uniformity; it is therefore done to decrease radial variation or imbalance.
The object of the present invention is to avoid the exponential increase of the rate of wear when signs of abnormal wear appear, or to decrease the rate of wear when the tire has molding defects. For this purpose, the invention proposes grinding the tire while respecting the basic harmonics of the out-of-roundness thereof (up to about harmonic 2).
Starting from the discovery that the rate of wear of a tire is not always linear, it has been observed that certain types of irregular wear can result in rapid acceleration of the rate of wear. The purpose of the invention is therefore to carry out a maintenance operation on the tire which consists of doing away with the incipient signs of irregular wear as soon as they are detected, or else a finishing operation which makes it possible to improve the geometrical character.